Written 2001
British Aerospace, now known as BAE Systems, has been in the aircraft design business for many years. Its history can be traced back to the amalgamation of many of the great British names in the aviation world. As the UK industry streamlined and the world aviation market became more competitive they have materialized as our only major aircraft manufacturer. Fortunately, BAE Systems can justifiably consider itself a world aviation company. Much of their success has been brought about by some classic aircraft, which have cemented their world position and perhaps more importantly their credibility. One such aircraft is the Hawk, which started off as the UK's main advanced trainer but has over the years developed into what it is today: a customer configurable Lead-In-Fighter aircraft. This extends the advanced trainer mission by adding the capability to drop weapons of all types. Also, in the Hawk 200, the aircraft has been developed into a light attack multi-role combat machine, equipped with an air-to-air radar.
The Australian Hawk 127. This aircraft is the most developed Hawk yet, configured with extremely modern avionics and a good weapons capability.
A TRAINER IS BORN
In the late 60's early 70's it was decided by the UK Ministry of Defence that a new principle advanced trainer and tactical weapons trainer would soon be required to replace the Folland Gnat and Hawker Hunter aircraft. In response to Air Staff Requirement 397, Hawker Siddeley offered the HS1182AJ advanced jet trainer design, which was subsequently selected in October 1971. In March 1972 an order was placed for 176 aircraft and the name was changed to Hawk. The first flight (XX 154) was made on 21 August 1974 from Dunsfold Airfield, Surrey. After a two-year flight test programme the RAF's first two Hawk T Mk 1s were delivered to Number 4 Flying Training School at RAF Valley, in November 1976. Their first use was to train the instructor pilots, with the first student flying starting in the summer 1977. The aircraft was given a further boost when, in late 1979, the RAF aerobatics display team, The Red Arrows, re-equipped with the aircraft. The tactical weapons trainer variant of the aircraft was designated the Hawk T Mk 1A.
As with all aircraft if the line is to be successful export orders are needed. With this in mind the Hawk 50 was developed with the aim of exploiting the basic aircraft's growth potential. It was also a chance to introduce a comprehensive ground attack capability. The principal differences of the Hawk 50 (first flight 17 May 1976) were an up-rated engine (5,200 lbst to 5,340 lbst), a revised tailcone to improve the high-Mach directional stability, two additional underwing pylons, enhanced cockpit instrumentation and reshaping of the ejection seat headbox to improve rearward visibility. 89 aircraft of the type were delivered.
From the Hawk 50 the Hawk 60 was developed as a refinement. The first flight was on 1 April 1982 and the main changes included a further increase in engine thrust (5,700 lbst), an aerodynamically refined wing with four stage flaps and the ability to carry larger external fuel tanks to increase the ferry range (65 per cent further than the T Mk 1). 144 aircraft were delivered between 1992 and 1998. Around the same time-frame the Hawk T45 Goshawk was being developed for the US Navy's carrier training requirements. This aircraft was greatly modified with a beefed up fuselage, undercarriage and wing, which also included full-span leading edge slats. It was also fitted with the highest rated engine yet fitted to a Hawk (6,030 lbst). The US Navy is intending to procure 234 Goshawks.
Taking The Hawk One Step Further
It soon became obvious that to keep up with modern avionics and weapons advances a very different Hawk was required. This came in the form of the Hawk 100 lightweight fighter and advanced systems trainer. All areas were up for redesign, except the basic shape. The Company demonstrator (G-HAWK/ZA101) was extensively modified to become the Hawk 100 prototype. It first flew in this form on 1 October 1987. However, the design underwent a further development programme in 1989 to re-emerge in 1990 with a new seven-station combat wing and an up-rated Adour engine. However, the cockpit did not receive its full update until February 1992 when the first definitive Hawk 100 (ZJ100) first flew. The main improvements in the Hawk 100 included an advanced cockpit with Multi-Function Displays (MFDs), Hands-On-Throttle-And-Stick (HOTAS) technology, a MIL-STD-1553B digital databus highway, seven-station combat wing with combat manoeuvring flaps and wingtip mounts for Sidewinder missiles, lengthened nose to house FLIR (Forward Looking Infra Red) and laser sensors, revised tailfin with Radar Warning Receiver (RWR) and an up-rated Rolls Royce Adour Mk 871 engine (6030 lbst). The aim of this aircraft was not only to serve as a Lead-In-Fighter trainer but also to be able to deliver US/NATO air-to-ground and air-to-air weaponry with a high degree of accuracy by day or by night. To date up to 117 aircraft have been ordered.
Taking the light multi-role combat aircraft theme one step further a single-seat variant was a logical offspring. This came in the shape of the Hawk 200, with its first flight on 19 May 1986. Here a single cockpit replaced the previous two cockpits and 80 per cent commonality with the Hawk 100 was maintained. The Northrop Grumman APG-66H radar system was added to offer seven air-to-air modes, five sub-modes for detection and tracking of airborne targets as well as a similar number of air-to-ground targeting modes. Other upgrades included an APU and a 25 kVa generator running the electrical system. To date 62 aircraft have been delivered.
The Australian Hawk
The final variant to date in this evolutionary chain is the Hawk 100 Lead-In-Fighter (LIF) that has been developed for an Australian order. Externally the aircraft was identical to any other Hawk 100 but some 'nice-to-have' features had been added. BAE Systems also informed me that it was now possible to customise the cockpit to match (as closely as possible) the main front-line fighter that the customer was operating. In the Australian's case it was the F/A-18 but the South African aircraft will be delivered looking more like a SAAB Gripen inside - a great capability for a LIF aircraft. The main improvements included three MFDs (in each cockpit), an enhanced HUD with F/A-18 symbology, revised HOTAS to be F/A-18-like, inertial nav/GPS, an APU, On-board Oxygen Generating System (OBOGS) and the provision for Air-to-Air refuelling (via a bolt on probe). The aircraft had a Night Vision Goggle compatible cockpit and external lighting, as well as a FLIR system. The electrical system had been upgraded with a 25 kVa generator and a Health and Usage Monitoring Systems (HUMS) provided a comprehensive fatigue monitoring capability.
The Royal Australian Air Force has ordered 33 aircraft with 12 being produced in the UK and the remainder in Australia.
ON TO FLYING
Having done my RAF advanced and weapons training on the Hawk T Mk 1/1A I was already familiar with the basic handling and operating qualities of the Hawk. I therefore concentrated my pre-flight study on the new systems and becoming familiar with the menu-driven MFDs. These were generally well laid out and intuitive. However, some of the deeper display options were slightly complicated and could do with some simplification. The transponder operation was one such process that needed to be simplified. After all, it is used frequently during a sortie. Gordon McClymont, one of the leading test pilots at Warton, who was looking after my visit and would be flying with me on the assessment, said that simplification of some of the modes was already in hand and that the Australian Hawks would be delivered with the new software. Gordon then proceeded to give me a complete rundown of the aircraft and how it differed from the original Hawk. He explained that if I considered it a mix between the Harrier II and the Hawk I would not be too far out, particularly in the cockpit (he did say that I was not to try and hover it though!). This put most things into perspective for me because the Harrier GR7 cockpit was modelled along similar lines as the F/A-18. After the systems brief we discussed the safety issues (what if it all goes wrong?), the operating area and the weather, which again was not being too kind and was raining. Why does an AFM assessment have to be in poor weather!? The basic sortie was going to comprise a formation take-off with another Hawk, general formation flying, general handling, stalling, spinning, some performance measurements, low-level flying including simulated weapons attacks and, finally, circuit work to include practice forced landings. An ideal sortie profile to get a good look at all features of the aircraft.
Safety equipment-wise my standard helmet, g-suit and other flying items were OK to be used, apart from the oxygen mask, which had a different impedance microphone to make it more compatible with modern radio systems. Thankfully, Mick in safety equipment had me sorted with all that was needed in minutes - thanks Mick very painless! With my flying equipment organized it was time to have a look at the aircraft in the hangar. This gave me a chance to 'play' with all the systems in the cockpit, with power connected, to get familiar with their operation before flight. It was also a good opportunity to ask Gordon any questions as I went along rather than trying to discuss systems detail in the air (wasting valuable flying time). I was surprised how similar to the Harrier (F/A-18) the cockpit was and I instantly felt at home. The majority of the menu functions were moded in a similar way to what I had been used to. As Gordon said that was the Idea of being able to configure your LIF aircraft to be similar to your main front-line fighter - I now understood what he meant.
After the familiarization in the aircraft it was back to the office for a quick cup of tea (we are British after all) and a formation brief with the other aircraft. This brief was a chance to cover all the peculiarities of operating in formation; for example, what power was going to be used on the take-off as well as other Standard Operating Procedures (SOPs) that were not necessarily standard to me. The brief lasted about 20 minutes and then it was time to walk for the flight.
Starting Was Simple
Once at the aircraft it looked very familiar; indeed, the walk round checks were almost the same as on the T Mk 1. Strapping in was like any other RAF modern aircraft and the seat felt comfortable. The before-start checks were a simple case of confirming that the few switches were in the correct place before starting the APU. The engine start itself was exactly as I remember on the standard Hawk and if I were being honest seems a little outdated know. However, Gordon did tell me that the next variant was being upgraded to the Adour Mk 951 engine, which not only produced 6,500 lbst but it was also controlled by a Full Authority Digital Engine Control (FADEC) system (like the AeroVodochody L159). After engine start the idle figures were 55% RPM and 270 TGT.
Ground Handling
Once started the aircraft was ready to taxy in one minute and 45 seconds! Taxying itself was very easy with a nosewheel steering system (NWS) (via the rudder pedals) replacing the old system of differential braking to steer. However, as an old-type Hawk pilot it was very difficult to stay off the brakes when I wanted to turn.. This would not be a problem after a little more familiarity with the aircraft or for pilots coming on to this model of Hawk as their first Hawk type. Similarly, it is more consistent with modern front-line fighters. Turns and tight manoeuvring on the ground were easy with no tendency to over-control.
The pre-take-off checks could be displayed on the MFD, which is a function I find very useful. It prevents errors being made and stops the need to have a paper checklist out when you are getting ready for take-off. With the checks complete it was time to give the emergency brief. This is given just before take-off and is a 'what-if' (the engine fails) brief. Thankfully, it was exactly the same as on the standard Hawk: if the engine fails below 250 knots eject; between 250 and 300 knots try an immediate relight but if unsuccessful eject; and above 300 knots we could try a turn back towards the airfield to see if we could glide to a runway; however, the option was always there to eject if it was not looking good (ground level, zero speed ejection seat).
Air Under the Wheels
With the emergency brief still in my mind I lined the aircraft up on the runway ready for take-off. The technique in the Hawk is to select full power and wait for the engine to settle so that a check of achieved parameters could be made (should change with a FADEC engine). However, on this occasion it was going to be a formation take-off, so after the full power check the engine was backed off a little to give me 'something in hand' to keep my formation position after brakes release. The other technique I use is to line up in a slightly more forward position than the normal formation position, again giving me more room for a slightly late brakes release and time to get the power sorted before I drop back too far.
After the power was set the standard nod of the head was given to indicate that the leader was releasing his brakes. With that we accelerated down the runway jostling slightly until I matched his thrust output exactly (made slightly more difficult because he was in a T Mk 1 Hawk with a different engine!). I eventually settled around 95% RPM, which was as low as I would want to go. Even with this power set we rotated at about 115 knots (211 kph), lifting clear of the ground at 123 knots (226 kph) after 20.3 seconds.
Formation Capability
Holding formation during undercarriage and flaps retraction was reasonably easy. During the cloud penetration to get into some clear air for the assessment we manoeuvred up to 50 degrees angle of bank, which again was not too difficult. The engine response and the control stick balance make the aircraft a good trainer for formation, as it is not too difficulty instilling confidence into the student. Once on top of the cloud we performed some more aggressive manoeuvring in formation up to approximately four g, which again was a relatively easy task (not as easy as in the Gripen but representative of the majority of front-line aircraft). Starting the sortie with a formation take-off followed by some aggressive manoeuvring was rather like being thrown in at the deep end; it is not possible to get an overall opinion of the aircraft when flying formation as all of your concentration (at least in my case) is being used to stay in position! - it was a welcomed break to move on to the general assessment!
General Qualities
Operating as a single aircraft I could explore the aircraft's handling and performance in a bit more detail. My first test was to look at the level acceleration capability. I was interested to see how it compared with the AeroVodochody L159 and the IAR SOIM aircraft, which are two of the Hawks competitors. Accelerating the Hawk at full power, at 8500 feet it went from 135 knots (248 kph) to 400 knots (736 kph) in one minute and twelve seconds. This was slightly slower than the L159 but quicker than the SOIM. The climb rate was also good at approximately 5900 feet per minute at 7500 feet. However, the Hawk really came into its own during general manoeuvring. The aircraft has always been a good 'turning' aircraft but with the addition of a combat flap system that could be selected below 350 knots (645 kph), the Hawk 100 was even better. When the combat setting was selected the flaps went down to 12½ degrees, thereby augmenting the lift generating capability of the wing, adding about an extra one 'g' to the instantaneous manoeuvre capability. Indeed, when performing a loop without combat flap selected at 300 knots (550 kph) it took 4,500 feet of airspace to complete the manoeuvre, whereas with combat flap selected it only took 3800 feet of airspace (for a four-g loop). When the speed was reduced to 250 knots (460 kph) the loop was completed in just over 2000 feet (starting at 9000 feet) - a very useful capability during air combat!
During my general handling there was a tendency for the 'Backup Oxygen' warning to sound when the throttle was brought to idle. This was because the main OBOGS did not quite produce enough oxygen at low thrust to keep the oxygen monitor happy. Gordon explained that the next modification was to add a bigger plenum chamber to the system to prevent these nuisance warnings.
Going Slow - Going Fast
Stalling the aircraft was very benign with not too much to report other than it stalled clean at approximately 15 degrees AoA (120 knots/220 kph), with a slight pitch nodding motion at full back stick. There was a small amount of airframe buffet at 10 degrees AoA. With gear and full flap down there was no natural aerodynamic stall warning and consequently an audio warning had been fitted that began sounding at 10 degrees AoA and increased in tone and assertiveness until the stall was reached at approximately 15-18 degrees AoA (100 knots/185 kph). The spinning, however, was more interesting because the aircraft was very reluctant to spin. The best technique to use was to enter from a 30-degree banked turn and at 160 knots (295 kph) put in full rudder in the required direction of spin and at the same time pull full back on the stick. From here the aircraft entered the autorotation stage with the nose initially coming up above the horizon before dropping rapidly down to about 65 degrees nose low. Once the nose had dropped the aircraft was continually trying to come out of the spin and did not always settle into a conventional spin. Indeed, for me the left spin was very gyratory, bucking wildly from about 70 degrees nose down, back up to about 20 degrees nose down. By this stage the aircraft was completing one full turn every 3.5 seconds; however, it was not uncomfortable to the extent of being worrying (at least not too much!) After about three turns the speed increased (approximately 10 knots per turn) indicating that the aircraft was not in a conventional spin and that a recovery had already occurred. Therefore, I centralized the controls and the spinning motion quickly stopped. Including the recovery we lost about 11,000 feet during the whole manoeuvre. The spin to the right was totally different: the entry was the same, as was the autorotation, but this time the aircraft settled into a reasonably stable spin. Again, the nose settled at 65-70 degrees nose down but the gyrations were not there. After four turns I initiated the same recovery actions as before and the spin stopped equally quickly. Again, about 11,000 feet was used for the manoeuvre but this time the aircraft was spinning slightly quicker at around 3.2 seconds per turn. Overall, the spinning qualities of the Hawk 100 were almost the same as those on the Hawk T Mk 1.
By contrast the high-speed qualities of this aircraft were much improved compared with the original Hawk, which used to have a small amount of directional (left to right) instability above about 0.8 Mach - not the case on the '100'. The aircraft was very stable at high Mach and even when trying to excite some instability with some sharp rudder inputs the aircraft was very docile. By this time the fuel was getting low and I still wanted to perform some low-level flight. Gordon explained that it was 30 or so miles to the best area, which gave me a chance to look at some of the systems. The navigational display was good with data being displayed both on the MFDs and the HUD. Steering to the waypoint was indicted by an upside-down 'V' on the heading scale that if aligned with the lubber line (heading reference mark) would take you to the waypoint. If you were steering to a target the lubber line was replaced by a diamond symbol. This helped with the situational awareness making it absolutely clear that the next steering point was the target.
Low Level and weapons
Dropping into low level (250 feet above the ground) the weather was not ideal; the wind was 40 knots (74 kph) and very turbulent and the visibility was not great with light rain showers around. However, the Hawk does have a good view out of the cockpit and the GPS navigation equipment was keeping me away from any restricted areas. The ride quality was not bad considering the strong winds and the turbulence coming off the hills. There was a very slight side to side motion (± ¼ of a degree) as the aircraft tried to cope directionally with the turbulence. Fuel consumption was 42 pounds per minute at 420 knots (775 kph) and 45 pounds per minute at 450 knots (830 kph). The aircraft could easily be flown at low-level speeds of between 360 knots (665 kph) and 480 knots (885 kph), which is ideal training for the majority of front-line fighters.
The very slight directional rock in the high winds appeared to have very little affect on the air-to-ground weapon aiming. Both in CCIP (continuously computed impact point) and CCRP (computer calculated release point) bomb modes the weapon attack run was reasonably easy to fly, giving good bomb release cueing. These modes basically involve flying a predicted bomb fall line through the target and then either releasing the bomb as the bomb aiming point goes over the target (CCIP) or committing to the attack with the target box on the target (CCRP). The air-to-ground guns mode was similarly simple to both interpret and to fly. The guns mode could use laser ranging with the correct equipment fitted (customer option) or could work on barometric or radalt height ranging. The range cue was very simple to interpret with a range ring unwinding to indicate the range reduction in thousands of feet.
Back To The Pattern
After about 15 minutes at low level the fuel bingo went off at 1000 pounds (455 kg) of fuel remaining, which meant it was time to move on to the circuit work. I climbed to about 5000 feet and eased back on the throttle to save fuel on the 30 nm (55 kilometre) transit back to Warton. During this bit of 'free' time I asked Gordon what the best range speed was and he explained that as the aircraft had an angle of attack (AoA) gauge you could simply fly at five degrees AoA and you would be flying at the correct range speed for any weight or configuration - a very useful capability that would be used again in the circuit. Flying at 290 knots gave a fuel flow of around 25 pound per minute (865 litres an hour). Gordon mentioned that at height this would come down to 18-20 pound per minute (625-695 litres an hour) but the ground speed would be much higher allowing greater distances to be covered (giving a quoted 1,400 nm (2,575 km) ferry range with external tanks).
Back in the pattern we used the ILS to line up on the final approach path and then proceeded to join for a run-in-and-break (the quickest way to rejoin involving running down the runway at high speed (450 knots/830 kph) followed by a hard turn into the pattern, while bringing the throttle to idle and putting the speedbrake out). When downwind it was nice to be able to put the flaps down below 250 knots (460 kph) instead of 230 knots (423 kph) on the old Hawk T Mk 1. The undercarriage was selected when the speed was less than 200 knots (365 kph) with 180 knots (330 kph) being achieved by the end of downwind before a further reduction to 160 knots (295 kph) around finals. Half way round the finals turn the AoA gauge was brought into use instead of the airspeed indicator converting to flying the rest of the approach at five degrees AoA. This was made easier by an 'E' shaped bracket in the HUD that represented a quick AoA reference without having to look into the cockpit at the AoA gauge. When the HUD reference mark was against the top line of the 'E' bracket it represented 7.5 AoA, against the middle line it represented 5.0 AoA and against the bottom line it equated to 2.5 AoA. It was simply a case of moving the throttle to make the 'E' bracket line up as required. The bracket was only displayed in the HUD with the undercarriage down. The final flare to landing was made by reducing the speed to 7.5 degrees AoA (top line of the 'E'). For the flight test we had very strong winds with about 20-25 knots of crosswind. However, using the wing-down crosswind technique (kicking off the drift at about 30 feet and holding straight down the runway with rudder and aileron) the landings were still very easy, with no tendency to skip or slid.
I also tried several practice engine failures from various positions and they where all relatively straight forward (once the strong wind had been allowed for!). The normal glide speed was 180 knots (330 kph) until sure of making the runway, although 5 degrees AoA was a more accurate best glide speed. The undercarriage was selected down when the runway could be reached, from here on a constant angle was maintained down to the runway. I like to keep high and then use the drag from full flap to get me down onto the runway. The nice thing about the Hawk is that once full flap is selected you can point the aircraft almost vertically down and the speed will not increase much. This is ideal for my 'yellow-streak', stay high, approach to engine failures.
On the final landing I wanted to try out a feature I had not seen on a Hawk before: the chute. This was slightly smaller than the chutes I had used on the Hunter or Jaguar but the principle was the same - to add extra retardation above and beyond the normal braking system. I am very much a pro-chute person as it can be used in lots of different ways. For example, it is very useful if you need to abort a take-off or if you are landing onto a short or wet runway but perhaps the most important use is in the case of an engine failure; here you can deploy it on touchdown to not only stop the aircraft quickly but hopefully to prevent it cart-wheeling if the landing is less than perfect. As far as using it on a normal circuit goes the pattern was flown exactly the same until touchdown, when I deployed the chute just as the main wheels touched the runway. The subsequent retardation was very impressive, slowing the aircraft from 117 knots (215 kph) to 60 knots (110 kph) in 14 seconds without touching the brakes! If I had used full braking as well (the brakes are protected by an anti-skid system) the stopping distance would have been very short indeed. Control throughout, including with the nosewheel off the ground, was very good, with very little pitch change on deployment.
In the hour and fifteen minute flight we had used approximately 2,400 pounds (1390 litres) of fuel. This equates to an average fuel burn of 32 pounds per minute or 1110 litres per hour, which is very respectable bearing in mind the sortie content: start up taxy and take-off, formation and aerobatics at high power settings with lots of throttle movements, 15-20 minutes at low level again at high power settings, approximately 10 minutes of systems checking at medium power settings, followed by the rest of the time in the circuit again using lots of throttle.
FINAL THOUGHTS
Overall, this model of Hawk was a marked improvement over the other Hawk models that I had flown. The handling and performance was similar to the Hawk T Mk 1 with the minor problems sorted out, making it a nicer aircraft to fly. However, the big improvements have been made in the cockpit. Here the systems can be customer specified to match as close as possible almost any front-line fighter, making the aircraft an excellent Lead-In-Fighter Trainer (LIFT). This particular Hawk was so similar to an F/A-18 that the student pilots would find the transition onto the fighter relatively easy, at least from a switching and moding perspective. Improvements are still being made with the introduction of a new engine with a Full Authority Digital Engine Control system and further improvements to the oxygen system coming in the near future. These are needed to keep the model at the cutting edge of the LIFT market. However, there is no doubt that BAE Systems have enjoyed a winning product over the years with the Hawk aircraft. The Hawk 127 appears to be an extension of that success, the problem now is where do they go from here? When this question was put to the BAE Systems Market Support Team they assured me that there were still plenty of upgrades in the pipeline - I look forward to being invited back to assess them in the near future!